1. Field of the Invention
The present invention relates to a dividing wall distillation column, and more particularly, to a dividing wall distillation column including a main column having a dividing wall, wherein the main column includes a pressure equalization unit for pressure equalization between a preliminary divisional section and a main divisional section, which are divided by the dividing wall.
2. Discussion of Related Art
In general, various source materials such as crude oil are often present as a mixture of numerous chemicals. Therefore, the source materials themselves are hardly used in industries, but are generally separated into respective compounds, which are used in these industries. A distillation process is representative of chemical processes for separating a mixture.
In general, the distillation process serves to separate the mixture into two components: a high boiling point component and a low boiling point component. Therefore, the distillation columns whose number (n−1) is smaller than the number (n) of components in the mixture to be separated by 1 are used. That is to say, a process for separating a three-component mixture has mainly used a structure in which two distillation columns are continuously operated on the spots of the conventional distillation industries.
A conventional distillation process for separating a three-component mixture is shown in FIG. 1.
The conventional distillation process uses a two-column system in which a lowermost boiling point component (D) is separated in a first column 11, and a middle boiling point component (S) and a high boiling point component (B) are separated in a second column 21. In this case, the middle boiling point (S) component may be generally remixed in a lower section of the first column.
The above-described conventional distillation process can easily control a composition of a product. However, since the middle boiling point component is remixed in the first column, a thermodynamic efficiency in the distillation column is degraded, resulting in unnecessary consumption of energy.
In order to solve these problems, much research on a new distillation structure has been conducted. A representative example of improving a separation efficiency using a thermally coupled structure may be a structure of a Petlyuk distillation column as shown in FIG. 2. The Petlyuk distillation column is arranged in a structure in which a preliminary separator 12 and a main separator 22 are thermally coupled. Therefore, a low boiling point component and a high boiling point component are primarily separated in the preliminary separator, and then flow to a feed plate of the main separator through a column-top portion and a column-bottom portion of the preliminary separator. Thereafter, the low boiling point, middle boiling point, and high boiling point components are separated in the main separator. This structure has high energy efficiency since a distillation curve in the Petlyuk distillation column is similar to an equilibrium distillation curve. However, the design and operation of a process are not easy, and the balance of pressure in the distillation column is particularly difficult to adjust.
In order to solve the problems regarding the Petlyuk distillation column, a dividing wall distillation column (DWC) has been proposed. A thermodynamic aspect of the DWC is similar to that of the Petlyuk distillation column, but a structural aspect is different from that of the Petlyuk distillation column in that a dividing wall is installed in a distillation column to integrate the preliminary separator of the Petlyuk distillation column in the main separator. Such a structure is highly advantageous in that operations are easily performed since the problems regarding the balance between the preliminary separator of the Petlyuk distillation column and the main separator are naturally solved and thus operations are simple, and the investment costs may also be significantly reduced since two types of distillation columns are integrated into one.